EVA Enhances the Interfacial Strength of EPS Concrete: a Molecular Dynamics Study

Expanded polystyrene (EPS) concrete has high environmental and economic benefits. However, the difference in physical and chemical properties leads to a weak interface between EPS and concrete, which limits the use of EPS concrete. Based on the macro experiment of Ethylene Vinyl Acetate Copolymer (EVA) modified EPS concrete, two molecular dynamics interface models of EPS/C-S-H and EPS/EVA/C-S-H were constructed by molecular dynamics simulation, and their interface strengthening mechanism was discussed. The results of interfacial interaction analysis show that EVA increases the interfacial interaction energy and binding energy between EPS and C-S-H, and improves the adhesion between EPS and cement base. The results of radial distribution function analysis show that in the model with the modifier, there are not only Van der Waals forces and hydrogen bonds in the model without the modifier, but also strong interactions such as Ca - = O and OT - = O. The results of mechanical property analysis show that the elastic modulus of EPS concrete interface model after adding modifier is improved, and its interface properties are improved. The molecular dynamics simulation carried out in this paper shows that EVA acts as a bridge between EPS and C-S-H and enhances its interfacial properties. This study can provide basic theoretical support for the application of EPS concrete and reference for the development of high-performance composite cement-based materials.